2. Urinary System Functions of Urinary System: 1.Excretion- removing nitrogenous wastes, certain salts and excess water from blood. 2.Maintain acid-base balance 3.Secrete waste products in the form of urine – remove waste from body 4.Eliminate urine from bladder

3. What if kidneys are not working properly?  Toxic wastes would accumulate in the cells, poisoning them

5. Kidneys  Bean-shaped organs  Located between peritoneum and the back muscles (RETROPERITONEAL)  Renal Pelvis- funnel shaped structure at the beginning of the ureter

8. Medulla  Inner, striated layer  Striated cones (divisions) are renal pyramids  Base of each pyramid faces cortex, while apex empties into cuplike cavities called calyces

9. Cortex  Composed of millions of microscopic functional units called nephrons

10. Nephrons  Functional unit of the kidney  Over 1 million in each kidney which comprise 140 miles of filters and tubes  Parts include: 1.Bowman’s capsule 2.Glomerulus 3.Proximal convoluted tubule 4.Loop of Henle 5.Distal convoluted tubule 6.Collecting tubule

12. Nephron structure  Afferent arteriole – blood from renal artery enters through this…  Bowman’s capsule – double-walled hollow capsule – surrounds glomerulus  Glomerulus – knotty ball formed from afferent arterioles finely dividing – contains 50 separate capillaries  Proximal convoluted tubule – twisted tubular branch off Bowman’s capsule

13. Nephron structure cont’d  Loop of Henle – proximal convoluted tubule descends into the medulla forming large loop  Distal convoluted tubule – ascending limb of Henle’s loop  Collecting tubule – distal tubule opens into collecting tubule

14. Secretion  Opposite of reabsorption  Secretion transports substances from blood into collecting tubules  Substances include creatinine, hydrogen ions, potassium ions, and some drugs  Electrolytes are selectively secreted to maintain body’s acid-base balance

15. Urinary Output  Average= 1500 ml/day  Urinalysis- examination of urine to determine presence of blood cells, bacteria, acidity level, specific gravity and physical characteristics (color, clarity and odor)  Normal in urinalysis =  Ammonia – not normal =  glucose, blood, pus

16. Ureters  One from each kidney  Carry urine from kidney to bladder  Smooth muscle tube with mucous membrane lining  Peristalsis pushes urine down ureters  The tubes that connect the kidneys and bladder.

17. Urine Formation in the Nephron 1- Filtration 2. Reabsorption 3- Secretion 3- Secretion

18. Filtration First step in urine formationFirst step in urine formation Blood from renal artery enters glomerulusBlood from renal artery enters glomerulus High blood pressure in glomerulus forces fluid (Filtrate) to filter into Bowman’s capsule (function of glomerulus is to filter substances from the blood)High blood pressure in glomerulus forces fluid (Filtrate) to filter into Bowman’s capsule (function of glomerulus is to filter substances from the blood) Filtrate does not contain plasma proteins or RBCs- they are too bigFiltrate does not contain plasma proteins or RBCs- they are too big Bowman’s capsule filters out 125cc of fluid/min. – 7500cc/hourBowman’s capsule filters out 125cc of fluid/min. – 7500cc/hour As filtrate continues through nephron, 90% of water is reabsorbedAs filtrate continues through nephron, 90% of water is reabsorbed

19. Reabsorption  Water and useful substances are reabsorbed  If blood levels of certain substances are high (glucose, amino acids, vitamins, sodium) then those substances will not be reabsorbed  Useful substances filter out of the renal tubules and back into the capillaries around the tubules = reabsorption

20. Path of urine formation  Glomerulus – Bowman’s capsule – proximal convoluted tubule – loop of Henle – distal convoluted tubule – collecting tubule – renal pelvis - ureter

21. Urinary Bladder  Hollow, muscular organ – in the pelvic cavity  Made of elastic fibers and involuntary muscle  Stores urine- usually about 500cc  Emptying urine (voiding) is involuntary but controlled through nervous system (voluntary)  Function = store and aid in elimination of urine  Urine leaves through urethra to outside opening = Urinary Meatus

22. Chemical Control  Reabsorption of H2O in distal convoluted tubule controlled by ADH (antidiuretic hormone)  Secretion and regulation of ADH controlled by hypothalamus  Diuretics inhibit reabsorption of H2O  Production of urine is controlled by ADH and aldosterone

23. Nervous Control  Direct control through nerve impulses on kidney blood vessels  Indirect control through stimulation of endocrine glands

24. Disorders of the Urinary System Renal Calculi (Kidney Stones)  Made of crystals of calcium phosphate and uric acid  Gradually they get larger until they block ureters  First symptom- severe pain  Other symptoms- nausea and vomiting, frequency, chills, fever, hematuria  Diagnosis- by symptoms, ultrasound, or x- ray  Rx- increase fluids to flush out stone, medications, and if needed- lithotripsy

25. Lithotripsy  Surgical procedure to remove kidney stones  Shock waves hit dense stones and break them up  Done on outpatient basis

26. Nephritis  Inflammation of the kidney (kidney infection) Incontinence =  Involuntary urination

27. Cystitis  Inflammation of the mucous membrane lining of the urinary bladder  Most common cause- E. Coli  Symptoms- Dysuria (painful urination) and frequency  Usually in females (shorter urethra)  Rx- antibiotics Updated July 29, 2005

28. Dialysis (Hemodialysis)  Used for kidney failure  Involves the passage of blood through device with semipermeable membrane  Dialysis serves as substitute kidney  Blood from patient flows through machine and if filtered  Can be done at home or in clinic  Takes 2-4 hours, 2-3 times a week

29. Kidney Transplant  As a last resort  Involves donor organ from someone with a similar immune system  Main complication- rejection

30. Terminology  Enuresis- bedwetting  Gylcosuria- sugar in urine  Nocturia- frequent urination at night  Polyuria- large amounts of urine  Anuria- no urine produced  Hematuria- blood in urine  Diuretic- drug or substance to increase urine production  Oliguria – decreased urine production (sign of kidney failure)